Endovascular intervention treatment is treatment for treating an affected area in the heart, brain, liver, or other organs by inserting a treatment tool (device) called a catheter into a blood vessel. For example, in endovascular intervention treatment, a doctor inserts a balloon-tip catheter to a stricture site. The doctor then, for example, injects fluid into the balloon through the catheter and expands the balloon. The stricture site is thereby expanded to restore the blood flow. The stricture site is thereby mechanically expanded to restore the blood flow. The balloon-tip catheter is pulled out of the body by the doctor after the fluid in the balloon is sucked.
In order to prevent restenosis of the stricture site expanded by the balloon, endovascular intervention treatment is conducted using a balloon-tip catheter having a metal mesh (stent strut) affixed to the outside of the balloon. In this treatment, the doctor expands the stent strut by expanding the balloon and thereafter sucks the fluid in the balloon and pulls the catheter out of the body. The expanded stent strut is retained at the stricture site, thereby reducing the possibility of restenosis at the stricture site. The balloon-tip catheter having a stent strut is called a “stent”.
In endovascular intervention treatment, it is necessary to move the device inserted into a blood vessel precisely to a treatment target site. In general, the device is positioned with reference to an X-ray image generated and displayed real-time by an X-ray diagnostic apparatus. For this purpose, the device has, for example, x-ray-opaque metal attached at two places (or one place in some cases) as markers indicating the position of the balloon or the stent. The doctor positions the device by referring to the markers visualized in the X-ray image appearing on a monitor.
However, when endovascular intervention treatment is conducted on a blood vessel in an organ such as the heart that always pulses or an organ that moves because of pulsation, the position of the device in the X-ray image always moves. It is therefore an extremely skillful task for doctors to position the device by referring to the X-ray image.
There is conventionally known a technique for displaying moving images in which the device appears virtually stationary, for example, by tracking the markers at two points visualized in the successively generated X-ray images and deforming the images such that the markers at two points in each X-ray image are located at the same positions as in the past images. A technique as a post-process is also known, which is for highlighting the device at a high contrast, for example, by obtaining the arithmetic mean of images of a plurality of frames in which the positions of the markers at two points are corrected to be the same position.